The present invention relates generally to rim and tire assemblies for pneumatic tubeless tires. More particularly, the present invention relates to a run-flat rim and tire assembly that has a friction member for preventing relative rotation between the rim and the tire.
During the twentieth century, tire designers and manufacturers have conceived of various designs with which to enable a pneumatic tubeless tire to continue to function even after a loss of air pressure. Generally, a tubeless fire is made of a tread section with two side walls. Beads are located at the end of each side wall and are typically rigid. The beads fit onto a rim. Putting air pressure into the interior of the tire causes the beads to seat against the rim and securely hold the tire onto the rim.
The design and use of a run-flat tire is desirable for several reasons. First, sudden loss of air pressure in a tire can result in a shifting of the position of the tire, and subsequently a change in the internal tensioning forces originally imparted by the tire on the rim to hold the tire thereon. The tire may become disengaged from the rim under certain circumstances.
Second, a loss of air pressure forces the tread of the tire down onto the rim. The rim must then assume the loading from the weight of the vehicle and the dynamic forces of the ride. As the rim is not designed for this purpose, damage to either the rim or even the wheel and axle supporting the rim can result. This in turn can lead to costly repairs in addition to leaving the driver and passenger stranded once the rim is too severely damaged to continue riding.
One such design of a run-flat tire is illustrated in U.S. Pat. No. 5,891,279 that is owned by the assignee of the present invention and is incorporated by reference herein in its entirety for all purposes. Tire and rim assemblies of this type have a flexible elastomeric material in the shape of a ring disposed on the rim. The tire surrounds this elastomeric ring. When the tire loses air pressure, the tire will deform and contact the elastomeric ring. The load of the vehicle and the dynamic load of the ride will then be born by the elastomeric ring. With reasonable and appropriate response by the driver of the vehicle, such design can improve vehicle control during a sudden loss of air pressure and can help protect the rim and other components. Run-flat tires are therefore desirable over conventional tires because with reasonable and appropriate action by the driver, such tires can help prevent accidents. Also, they allow drivers additional mileage by which to travel to a location where the tire can be inspected and repaired or replaced.
Sometimes during run-flat driving the elastomeric ring could possibly slip in relation to the tire which can result in the heating-up of the components and faster thermal degradation of the tire.
Increased weight on the axles of vehicles may be undesirable to automobile manufacturers because this weight reduces the handling abilities of the vehicle. It may therefore be desirable to decrease the weight of run-flat tire assemblies, and not to increase the weight of run-flat tire assemblies.
The present invention improves upon previous run-flat tires by preventing or reducing slippage between the tire and the rim during run-flat operation. As a result, the amount of heat and subsequent degradation of the tire and elastomeric ring during run-flat operation are reduced by the design of the present invention.
Objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned from practice of the invention.
The present invention provides for a tire apparatus that is used for driving a vehicle during periods of low tire pressure and normal tire pressure. The tire apparatus includes a rim that has a first bead seat and a second bead seat. The rim has a cylindrical section that is between the first and second bead seats. The rim is configured for attachment to a wheel of the vehicle. A support ring is disposed on the cylindrical section of the rim. The support ring is configured for supporting the vehicle during periods of low tire pressure. Also, a tire is provided that has a tread portion and a pair of side walls that are adjacent to the tread portion. The tire has a first bead at one end of one of the side walls and a second bead at one end of the other of the side walls. The first bead is disposed in the first bead seat and the second bead is disposed in the second bead seat. At least one of the first and second bead seats has a plurality of friction members, that are disposed thereon, to prevent relative rotational movement between the tire and the rim. The first bead and the first bead seat form a first air seal zone, and the second bead and the second bead seat form a second air seal zone. The friction members are spaced from the first and second air seal zones.
Alternatively, the present invention may include an embodiment of a tire apparatus as previously discussed where the friction members are ridges on the surface of the bead seats. The ridges are oriented in a substantially axial direction.
Also, another embodiment of the present invention exists in a tire apparatus as discussed above where the friction members are depressions in the surface of the bead seats. The depressions are oriented in a substantially axial direction.
A further embodiment of the present invention exists in a tire apparatus as discussed above where the friction members are ridges on the surface of the bead seats with depressions in the surface of the bead seats located immediately adjacent thereto. Both the ridges and the depressions are oriented in a substantially axial direction.
The present invention also encompasses a tire apparatus as discussed above where the friction members are grit or roughness on the surface of the bead seats.
Another embodiment of the present invention may include a tire apparatus for driving a vehicle during periods of low tire pressure and normal tire pressure. The tire apparatus encompasses a tire that has a tread section where the tire has a pair of side walls located adjacent to the tread section. A first bead is located at one end of one of the side walls and a second bead is located at an end of the other side wall. A rim is also included that has a first bead seat and a second bead seat. The rim is configured for attachment to the wheel of a vehicle, and the rim has a support member for engaging the tire during periods of low tire pressure to allow the vehicle to be driven during periods of low tire pressure. At least one of the first and second bead seats has a plurality of friction members to prevent relative rotational movement between the tire and the rim.
Another embodiment of the present invention includes a tire apparatus as immediately discussed where the friction members are ridges on the surface of the bead seats. The ridges are oriented in a substantially axial direction.
Another embodiment of the present invention may include a tire apparatus as previously discussed where the friction members are depressions in the surface of the bead seats. The depressions are oriented in a substantially axial direction.
A still further embodiment of the present invention exists in a tire apparatus as previously discussed where the friction members are ridges on the surface of the bead seats along with depressions in the surface of the bead seats located immediately adjacent thereto. Both the ridges and the depressions are oriented in a substantially axial direction.
Alternatively, the present invention may include an embodiment of the tire apparatus as discussed above where the friction members are grit on the surface of the bead seats.
A still further embodiment of the present invention exists in a tire apparatus for driving a vehicle during periods of low tire pressure and normal tire pressure. The tire apparatus includes a rim that has a first bead seat and a second bead seat. The rim has a cylindrical section intermittent the first and second bead seats. The rim is configured for attachment to a wheel of the vehicle. A support ring is disposed on the cylindrical section of the rim. The support ring is configured for supporting the vehicle during periods of low tire pressure. Also, a tire is present that has a tread portion and a pair of side walls that are adjacent the tread portion. The tire has a first bead at one end of one of the side walls and a second bead at one end of the other of the side walls. The first bead is disposed in the first bead seat and the second bead is disposed in the second bead seat. At least one of the first and second bead seats has grit disposed thereon to prevent relative rotational movement between the tire and the rim. The first bead and the first bead seat form a first air seal zone, and the second bead and the second bead seat form a second air seal zone. The grit is spaced from the first and second air seal zones.
Yet another embodiment of the present invention exists in a tire apparatus for driving a vehicle during periods of low tire pressure and normal tire pressure. The tire apparatus has a tire with a tread section. The tire also has a pair of side walls located adjacent the tread section. A first bead is located at an end of one of the side walls, and a second bead is located at an end of another one of the side walls. At least one of the first and second beads has a plurality of friction members to prevent relative rotational movement between the tire and a rim. The rim has a first bead seat and a second bead seat. The rim is configured for attachment to the wheel of a vehicle. The rim has a support member for engaging the tire during periods of low tire pressure to allow the vehicle to be driven during these periods.